Elevator safety device.



R. C. SMITH.

ELEVATOR SAFE-TY DEVICE.

APPLICATION FILED MAY'Z. 1910.

1 1 83, 1 3 1 Patented May 16, 1916.

@MAQSWLZE, 2mm

WJZM M UNITED STATES PATENT, OFFICE.

BU'DOLPH G. SMITH, OF YONKEERS, NEW YORK, ASSIGNOR TO OTIS ELEVATOR COM- PANY, OI JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

ELEVATOR SAFETY nEvIoEl Specification or: Letters Patent.

PatentedMay 16, 1916.

Application filed May 2, 1910. Serial No. 558,765.

T 0 all whom it may concern:

Be it known that I, RUDOLPH C. S ITH, a citizen of the United States, residing at Yonkers, in the county of Westchester and State of New York, have invented a new and useful Improvement in Elevator Safety Devices, of which the following is a specification. 1

My invention relates to frictional driving apparatus and one of its objects isthe provision of a safety device comprising a movable tension beam to prevent the car from traveling beyond a predetermined point.

More particularly it is the object of the present invention to provide a safety device for a frictional driven elevator whereby the tension of the power transmitting means is diminished to preventthe'car from going beyond a predetermined limit of travel.

Other objects of the invention will appear hereinafter, the novel combinations of elements being pointed out in the claims.

This application covers subject-matter included in my prior abandoned application,

' Serial No. 332,051, filed August 25, 1906,

for traction elevator system.

In the accompanying drawing, C designa'tes the elevator car or load-carryingdevice which travels on the vertical guide rails 1, 2 in the usual manner, and is suspended by any desirable number of cables 3. These cables pass over the suspension sheave 4 near the top of the elevator well and thence downwardly to the counterweight 5 where they are connected at 33 to the yoke 34.

The sheave 4 is mounted on the movable tension beam 6 which is pivoted at 7 to the fixed beam 8. The fixed beam 9 on the opposite side carries a lever 24 pivoted at 26, and extending into the elevator Well in the path of the detent or striking block 17 on the top of the car and immediately below the outer end of the beam 6. A stop pin 27 maintains the lever 24 in a substantially horizontal position and a projection 25 extends upwardly from the lever 24.

To the outer end of the movable beam 6 is secured the driving cable 11 forming part of means for transmitting power from the driving sheave 13 to the car C and coun-" terweight 5. The cable 11 leads upwardly over the direction sheaves 12, 12' mounted on the overhead beam 19 and thence downwardly to the loose sheave 15 on the upper side of the counterweight. Passing around the lower portion of said sheave the cable 11 then passes upwardly to the fixed sheave 18 on the beam 19, and thence downwardly around the lower portion of the driving sheave or drum 13, upwardly around the movable sheave 16 on the lower side .of the counterweight 5 and finally to the fixed point 23.

The driving sheave 13 may be connected to any suitable type of motor which is here shown merely by way of illustration as an electric motor. This motor may be controlled in any desired manner, as by means of a switch 22 in the car and a starting rheostat 2'0. 1

21 designates a source of power of the controlling circuits.

It will be seen that normally the driving rope is held in tension by the pivoted beam 6 together with the car, sheave 4, counterweight 5, and cable 3 supported thereby.

'When any variations occur in the load as when inertia is to be overcome, the tension beam will come into play to counteract any tendency to slackening of the driving rope 11. The tension beam will act to change the tension on the part slackened seats to make the tension substantially constant throughout and in direct proportion to the load. Now when the car is lifted by the frictional driving apparatus and power transmitting means until said car approaches its extreme upper limit of travel, the detent or driving block 17 will engage the lever 24 and move the same upwardly and the projection 25 will exert an upward pressure on the lever 6.

If after the block 17 strikes the lever 24 the frictional driving apparatus continues to lift the car, the beam 6 will be carried upwardly and the upper portion of cable 11 slackened. It will be noticed that when the car causes the beam 6 to move, the suspension sheave 4 will also move upwardly thereby tending tolift the counterweight 5 to counteract the slackening effect. But it should be noted that the point 10 on the outer end of the beam will have a greater movement in the arc of a circle with 7 as the center than that portion of the suspension cable 3 directly above the counterweight 5. The resultant action will therefore be a downward movement of counterweight 5 and a consequent loosening or slackening of the driving rope without producing any corresponding upward movement of the car C.

the friction sheave 13 will be lessened to such an extent that the friction normally existing between the sheave l3 and the driving cable 11 will be decreased allowing the motor to continue to rotate freely until the normal 57 frictional engagement between the driving sheave 13 and the driving cable 11 is reestablished. Before this occurs, however, the operator in the car can move the switch 22 to central or stop position so as to stop the motor, and after the tension is reestablished, the car will be stopped also.

From the foregoing description it will be evident that any excessive upward travel of the elevator car tends to slacken the driving cable and thus allows the hoisting motorshea-ve to slip Without producing any fur ther upward movement of the car, and upon stopping the motor the several parts automatically return to normal operating conditions and consequently there is no necessity for the elevator attendant to reset by hand the limiting device which is always the case when the ordinary type of stop-motion is used. In other words, I have constructed an automatic or self-restoring limit stop device for traction or frictionally driven elevators.

Obviously those skilled in the art may make various modifications in the details and arrangement of parts Without departing from the spirit and scope of my invention and I desire therefore not to be limited to the precise construction herein disclosed.

What I claim and desire to have protected by Letters Patent of the United States is 1. In a traction elevator, the combination of a car and counterweight, a cable connected to the car and counterweight, a sheave over which said cable passes, a pivoted beam supporting said sheave, a driving cable connected to said beam and associated with the counterweight, a lever adapted to rock said beam upon its pivot, and means carried by the car co-acting with said lever to effect a slack in the said driving cable when the car reaches a predetermined position in its travel.

2. In a traction elevator, the combination of a pivoted beam, a sheave carried by said beam, a cable associated with said sheave, a car and counterweight suspended from opposite ends of said cable, an additional cable connected at one end to said beam and at its other end to a fixed point, an operative connection between said additional cable and the counterweight, frictional driving means associated with said additional cable, and means comprising a lever adapted to be engaged by the car at the upper limit of car travel for varying the position of said beam and one end of said additional cable and thereby effecting a slack in the latter.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

RUDOLPH C. SMITH.

Witnesses:

L. H. CAMPBELL, JAMES G. BETHELL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents Washington, D. G. 

